There are a great many types of portable signs that are used for temporary display of warnings, advertisements and the like. One of the more common types of signs, particularly in the highway construction sign industry, involves a single vertical staff with a mechanism on the top of the staff for supporting the sign and a base. The base, in many examples, is made up of a plurality, three or four usually, legs that in the storage and handling position fold up adjacent to the staff or the staff holder and in the use position fold outwardly to support the staff vertically above the ground, pavement, or other surface.
There are many kinds of mechanisms for locking the leg in one of two or more positions. One position is the storage position with leg locked adjacent the staff or staff holder. The other position is the extended position for supporting the staff vertically on a surface. The legs may also be positionable in a plurality of orientations relative to the staff to provide a higher or lower support, to accommodate differences in the support surface, e.g. a rough or uneven support surface. While many extended positions can be provided, the fundamental premise is that there is at least one extended position. It is to a mechanism for locking the device in the storage position and, selectively, locking the legs in the extended use position that the present invention is directed.
One mechanism commonly used involves the plurality of plates extending from the staff or staff base, a leg pivotly connected at the proximal end to the plate, and a mechanism for locking the leg in the storage position adjacent to the staff or in the extended position. One of the mechanisms for providing such locking comprises a plate attached to the staff or staff base having an aperture adjacent the staff or staff base and having another aperture spaced outwardly from the staff or staff base. The plate, in this type of device, extends outwardly from the staff base with a locking mechanism slightly outwardly disposed relative to the pivot mechanism. The locking device engages, selectively, the aperture adjacent the staff base or the aperture distal from the staff base, both aperture lying on arc of a circle in which the pivot is the center point. The locking mechanism, alternatively, is engaged in the plight distal from the staff base. In this type of sign, there have been generally two types of approaches. In one approach, a boss, pin or other extension is formed on or attached to the leg. The leg is forced away from the plate so that the pin or boss is removed from the aperture and the leg is then pivoted to the desired position. In this kind of mechanism the boss or pin usually rides against the plate. The natural result of this type of mechanism is that movement is rather difficult and the boss or pin wears a groove in the plate. This, in turn, often makes operation more difficult. Generally speaking, this type of mechanism is useful but not fully satisfactory.
Another type of mechanism is similar except that rather than having a boss or a pin extending permanently from the leg, a resiliently biased pin is provided for insertion into the respective aperture in the plate. In operation, the user must reach down and pull the string biased pin outwardly, freeing it from the aperture, and then moves the leg to the desired position and return the pin, using its natural resilient mounting, into the selected aperture. This mechanism solves the problem of gauging the plate, as previously described. However, this mechanism is not entirely satisfactory because it requires that the operator bend over each time a leg is moved, either from the storage position to the support position, or vise-a-versa, or to any of the alternative positions if a plurality of such positions are provided by way of a plurality of aperture. This is not only time consuming, but it is tiring and sometimes difficult for those who have back problems.
The present invention solves both of the aforesaid problems by a unique interacting combination of mechanisms, which individually, are previously known in the art.